Process of increasing the dye receptivity of undyed polyamide

ABSTRACT

A PROCESS OF IMPROVING THE DYE RECEPTIVITY OF AN UNDYED TEXTILE PRODUCED FROM A FIBER-FORMING SYNTHETIC LINEAR POLYCARBONAMIDE HAVING RECURRING AMIDE GROUPS AS INTEGRAL PARTS OF THE MAIN POLYMER CHAIN COMPRISING CONTACTING AT A TEMPERATURE OF AT LEAST ABOUT 25*C. AND FOR AT LEAST ABOUT ONE MINUTE THE ARTICLE WITH A SOLUTION CONSISTING ESSENTIALLY OF A COMPOUND SELECTED FROM PYRIDINE AND SUBSTITUTED PYRIDINES AND WATER AT A WEIGHT RATIO OF FROM ABOUT 95:5 TO ABOUT 5:95, REPECTIVELY, AND THEN REMOVING THE PYRIDINE OR SUBSTITUTED PYRIDINE COMPOUND FROM THE ARTICLE.

United States Patent Office 3,595,606 Patented July 27, 1971 3,595,606 PROCESS OF INCREASING THE DYE RECEPTIVITY F UNDYED POLYAMIDE James P. Kimbrell, In, and Graham Chantrey, Decatur, Ala., assignors to Monsanto Company, St. Louis, M0. N0 Drawing. Filed May 1, 1967, Ser. No. 634,831 Int. Cl. D06m 3/30 US. Cl. 8130.1 8 Claims ABSTRACT OF THE DISCLOSURE A process of improving the dye receptivity of an undyed textile produced from a fiber-forming synthetic linear polycarbonamide having recurring amide groups as integral parts of the main polymer chain comprising contacting at a temperature of at least about 25 C. and for at least about one minute the article with a solution consisting essentially of a compound selected from pyridine and substituted pyridines and water at a weight ratio of from about 95:5 to about :95, respectively, and then removing the pyridine or substituted pyridine compound from the article.

BACKGROUND OF THE INVENTION Field of the invention The field of art which is applicable to this invention is textiles produced from a fiber-forming synthetic linear polycarbonamide ha ving recurring amide groups as integral parts of the main polymer chain and to the dyeing of these textiles by an aqueous solution comprised of pyridine or a substituted pyridine compound (the substituted groups can be aryl, alkyl, carboxy, hydrohalide, etc.) washing the pyridine compound out of the textile and then applying the dye to the textile to impart color thereto.

Description of the prior art Textiles produced'from a polyamide have limited affinity for dyes. This is due partly to the low afiinity of polyamide for water, i.e. it is not easy to obtain good penetration of the textile with aqueous dyestufr solutions. Also, the affinity of the polyamide for a particular dye is directly dependent upon the degree of orientation, i.e. the higher the degree of orientation or the closer the molecules are packed within the fiber the lower is the afiinity 0f the textile for the dye.

SUMMARY OF THE INVENTION It is an object of this invention to provide a novel process for increasing the dye receptivity of a textile produced from a fiber-forming synthetic linear polycarbonamide.

It is another object of this invention to provide a process of increasing the dye receptivity and the uniformity of dyeing a textile produced from a fiber-forming synthetic linear polyc'arbonamide.

Other objects of this invention will become apparent as the invention is fully developed within the specification and claims.

These and other objects of this invention are accomplished by providing a process of increasing the dye receptivity of a textile produced from a fiber-forming synthetic linear polycarbonamide having recurring amide groups as integral parts of the main polymer chain comprising contacting at a temperature of at least about C. and for at least about one minute the article with a solution consisting essentially of a compound selected from the group consisting of pyridine and substituted pyridine compounds and water at a weight ratio of from about 95 :5 to about 5:95, respectively, and then removing substantially all of the pyridine or substituted pyridine compound from the article. Contacting the article can be effected at a temperature of at least about 25 C. and the temperature can be up to about the boiling point temperature of the solution containing the pyridine or substituted pyridine compound and water. The contact time can vary from a few seconds up to a time in excess of five minutes; however, an appreciably noticeable improvement is effected on the textile after about one minute and is fully effected on the article at about five minutes. After the textile is contacted with the above solution it is washed to remove the pyridine or substituted pyridine compound from the textile. A cross sectional analysis of a fiber treated by this invention compared to a fiber not treated by the invention reveals that the pyridine or substituted pyridine compound and water solution swell the fiber and that after the pyridine or substituted pyridine compound is removed from the fiber, water is left in the fiber to sustain the swelling effect imparted thereto. The dye re ceptivity of a textile treated by this invention is improved with dyes such as acid, disperse, metal complex, direct and basic dyestuffs and, in addition, the dyeing uniformity is increased when dyeing the textile with these dyestuffs.

DESCRIPTION OF THE INVENTION In accordance with this invention, an increased dye receptivity of a textile produced from a fiber-forming synthetic linear polycarbonamide is effected by a process comprising contacting the textile with a solution consisting essentially of a compound selected from the group consisting of pyridine and substituted pyridine compounds and water and then removing the pyridine or substituted pyridine compound from the textile. The textile can be contacted with the solution at a temperature of at least about 25 C. and the temperature can be as high as the boiling point temperature of the solution. Temperatures lower than 25 C. are also useful but at the lower temperatures the contacting is not as efiicient as at higher temperatures. Preferably, the contacting temperature is within the range of from about 40 C. up to about the boiling point temperature of the solution. The period of contact time should be sufficient to thoroughly wet the textile, i.e. for at least about one minute, however noticeable effect of the improved dye receptivity can be observed at contact times of a few seconds. However, it is preferred that the contact time be about 5 minutes to give sufficient wetting of the textile with the solution.

The textile can be contacted with the pyridine or substituted pyridine compound and water solution by any conventional method. For example the solution can be padded on the textile, the textile can be run through an exhaust bath containing the solution, the textile can be contacted with vapors of the solution (an example of this method would be containing the textile in an atmosphere comprised of vapors of the solution), the textile can also be contacted with liquid or vapors containing the solution and then fed on a tenter frame where steam or dry heat is applied to the textile, or by any method conventionally used in the dyeing or finishing art.

The solution consisting essentially of pyridine or a substituted pyridine compound and water should be at a weight ratio of from about 95:5 to about 5:95, respectively, and preferably from about :10 to about 10:90, respectively. More preferably, the pyridine or substituted pyridine compound and water are at a weight ratio of about 30:70, respectively.

As mentioned earlier, the pyridine or substituted pyridine compound is removed from the textile before the dye is contacted with the textile. There should be sufficient water within the solution so that after the pyridine or subsituted pyridine compound is removed from the article, water will be left as residue within the textile to maintain the swelling effect that the solution had imparted thereto.

It is hypothesized that the residue water forms hydrogen bonding with appropriate reactive groups in the synthetic linear polycarbonamides and also that van der Walls forces act to retain the water molecules within the textile to maintain the swelling effect thereof.

A textile treated by the teaching of this invention exhibits improved dye receptivity with acid, disperse, metal complex, direct, and basic dyestuffs and, in addition, exhibits improved dye uniformity. The mechanism for the increased dye receptivity is thought to be that the dye molecules are more readily attached to the textile when the textile is swollen by the solution containing the pyridine or substituted pyridine compound and water. Also, it is thought that the water retained in the textile after the swelling action helps to solubilize the dye molecules on the textile.

The term textile as used herein is meant a fiber, filament, yarn, fabric and any like or similar produced figuration.

The textile useful in this invention is obtained from a fiber-forming synthetic linear polycarbonamide having recurring amide groups as integral parts of the main polymer chain, i.e. the polymer has recurring units of the formula I ll wherein R is hydrogen or a monovalent hydrocarbon radical as integral parts of the main polymer chain, the average number of carbon atoms separting the amide groups being at least about 2. Examples of polycarbonarnides useful with this invention can be found in US. Pat. Nos. 2,071,250; 2,071,253; and 2,130,948. In particular, the invention is applicable to polycarbonamides such as are formed from the condensation of tetra-methylene diamine and adipic acid, tetramethylene diamine and suberic acid, tetramethylene diamine and sebacic acid, hexamethylene diamine and adipic acid, hexamethylene diamine and suberic acid and hexamethylene diamine and sebacic acid. Broadly, the invention is anticipated to cover polycarbonamides formed from the condensation of a diamine and a dicarboxylic acid as well as those formed from the interpolymerization of a monoaminomonocarboxylic acid.

The term pyridine and substituted pyridine compound as used in this invention is meant to include pyridine, alkyl substituted pyridines (the alkyl grouping containing from 1 to about 10 aliphatic carbon atoms) such as lutidine and collidine; carboXy substituted pyridines compounds such as picolinic acid, nicotinic acid, isonicotinic acid, and quilonic acid; aryl substituted pyridine compounds such as quinoline; N-alkyl substituted pyridine halides (the alkyl grouping containing from 1 to about 10 aliphatic carbon atoms) such as cetyl pyridinium bromide; and hydrohalide substituted pyridine compounds such as pyridine hydrochloride. Pyridine is the preferred compound useful in this invention.

As mentioned previously, the dye receptivity of the textile is improved by the teachings of the invention. Specific dyes which are applicable are any conventional dye used on fiber-forming synthetic linear polycarbonamides. For example, the dye receptivity of the textile is improved when contacted with acid, disperse, metal complex, direct and basic dyestuffs.

The following examples are presented to specifically illustrate working embodiments of the invention. These examples are not intended to limit the invention in any way. In the following examples, the ingredients in the dye-bath composition are reported as percent by weight, based on weight of the textile.

EXAMPLE 1 Samples of textureed nylon are immersed for 5 minutes in boiling solutions containing pyridine and water at weight ratios of :90, :80, :70, :60, :50, :40, :30 and :10, respectively. The samples are then removed from the solution, washed with tap water at ambient temperature until all of the pyridine is removed from the samples, air dried, and scoured for 30 minutes at the boil in an aqueous solution containing 1% of sodium carbonate and 2% of a polyethylene ether (Triton X-67, a trade name of Rohm & Haas Co., 222 W. Washington Square, Philadelphia, Pa.). The samples are then dyed by immersing them for 3.0 minutes at C. in an aqueous solution (liquor to goods ratio being 40:1) containing 2.0% of C. I. Direct Blue 71 and 3.0% of ammonium acetate. The test samples when compared to control sample (not treated by the pyridine and water solution) indicated that they were colored a darker blue than the control samples. The solution containing a composition of pyridine and whater at a weight ratio of 30:70, respectively, indicated the greatest difference in depth of color when compared to the control sample.

EXAMPLE 2 The procedure of Example 1 is repeated except the solution of the pyridine and water is at a weight ratio of 30:70, respectively, and the samples are immersed in the solution at times of 5, 10, 15, 30, 60, 120, and 960 minutes. These samples indicated that the shade of color was not improved after boiling times longer than 5 minutes.

EXAMPLE 3 Samples of polyamide fiber obtained from the polymerization of adipic acid and hexamethylene diamine are immersed for 5 minutes in a boiling solution containing pyridine and water at a weight ratio of 30:70, respectively. The samples are then washed at ambient temperature with tap water to remove the pyridine and are then extracted with carbontetrachloride at room temperature. Thereafter, the samples are air dried and are then scoured for 30 minutes at the boil in an aqueous solution containing 1% "of sodium carbonate and 2% of Triton X67. The samples are then dyed by immersing them in aqueous dyebaths at 100 C. (liquor to goods ratio being 40:1) at various periods of time (t) ranging from 1 to 12 minutes, the dyebaths containing 2.0% of C. I. Direct Blue 71 and 3.0% of ammonium acetate. Also, the dyebaths containing the samples are permitted to come to equilibrium, i.e. the samples are permitted to exhaust or absorb as much of the dye as possible. The optical densities of the exhausted dyebaths are determined spectrophotometrically and from this data the amount of dye absorbed on the sample is calculated. From this data, a plot is made of C /Ca versus /time, C represents the amount of dye absorbed on the sample at time t didived by the weight of the sample and this quotient multiplied by 100, and CW represents the amount of dye absorbed on the sample at equilibrium conditions between the sample and the dyebath divided by the weight of the sample and this quotient multiplied by 100. The time where C /Cm is equal to 0.5 is determined from the plot and this is the time of half dyeing, fl/z. From these data, the specific rate constant of the dyeing is calculated from the following formula:

TABLE I Test sample (treated Control Data with pyridine/water) sample t% (time of half dyeing) 3 minutes 13 minutes. Cm (equilibrium absorption)... 1.48% 1.23%. K (dyeing rate constant) 0.76 0.30.

These above data indicate that the test sample dyes more than twice as fast as the control sample. In addition, the degree of dye penetration of the dyestuif in the samples is analyzed at various stages of the dyeing process and it is found that the dye penetrated more rapidly into the test sample than the control sample, thus indicating a more open and less ordered structure, e.g. the dye takes about 16 hours to completely penetrate the control sample whereas it takes only 30 minutes to completely penetrate the test sample.

EXAMPLE 4 Samples of regular nylon obtained from the polymerization of adipic acid and hexamethylene diamine and samples of acid dye resist nylon (i.e. nylon obtained from the polymerization of adipic acid and hexamethylene diamine but having an acidic character built into the fiber) are treated as described in Example 2 except the samples are immersed for 5 minutes in the pyridine and water solution and dyed by two different procedures:

Procedure No. 1.-Five samples each of regular nylon and dye resist nylon are immersed for 30 minutes at 95 C. in separate aqueous deybaths (liquor to goods ratio being 40: 1) containing 5.0% of ammonium acetate, 1.0% of acetic acid and 1% each of one of the below indicated dyes: C. 1. Basic Red 17; C. I. Basic Blue 22; Astrazon Yellow 7 GLL (a trade name of Verona Dyestulfs, a Division of Verona-Pharma Chemical Corp., Springfield Road, Union. N.J.); C. I. Basic Red 14, and Deorlene Blue 56 (a trade name of Ciba Chemical & Dye Company, Tap Division, Fair Lawn, N.I.).

Procedure No. 2.-Five samples each of regular nylon and dye resist nylon are immersed for 30 minutes at 95 C. in aqueous dyebaths (liquor to goods ratio being 40:1), each dye bath containing 1.0% of one of the above indicated dyes and containing 5.0% of ammonium acetate.

The above test samples compared to control samples indicate that the former have a higher dyeing rate and contain more dye or color than the control samples and that the acid dye resist nylon has a higher saturation value of the dye than similar control samples.

EXAMPLE 5 Samples of regular nylon and acid dye resist nylon are treated as described in Example 2 except the samples are maintained for 8 minutes in a boiling solution of pyridine and water at a weight ratio of 30:70, respectively, and are then dyed to equilibrium by being immersed for 6 hours at 100 C. in an aqueous dyebath (liquor to goods ratio being 40:1) containing 6.24% of C. I. Basic Blue 22, 5.0% of ammonium acetate and 1% of acetic acid. The test samples of the regular nylon and the acid dye resist nylon, as compared to respective control samples, indicate that the test samples absorb more of the dye than the control samples, these results being indicated in Table II:

TABLE II Amount of dye absorbed on the sample Sample: (percent O.W.F.)

Regular nylon:

(1) Control sample 0.15 (2) Test sample (treated with pyridine/ water) 0.32 Acid dye resist nylon:

(1) Control 1.00 (2) Test sample (treated with pyridine/ water) 1.90

These above data indicate that the invention is applicable to regular nylon fibers, i.e. fibers which do not contain additional reactive acidic groups thereon, as Well as acid dye resist nylon fibers, i.e. nylon fibers which contain thereon acidic groups on the fiber to attract basic dyestuffs but to resist acidic dyestuffs being attractive to the fiber. As the above data indicate, the acid dye resist nylon has some attraction for the basic dyestufls but the attraction is weak as compared to the test sample and the test sample indicates that a large number of dyestuif molecules can easily penetrate into the interior of the fiber, thus producing an increased basic dyeability of the acid dye resist nylon.

EXAMPLE 6 A nylon fabric having yarns containing fibers obtained from the polymerization of adipic acid and hexamethylene diamine, the yarns having draw ratios from 2.91 to about 3.61 are maintained for 5 minutes in a boiling solution containing pyridine and water at a Weight ratio of 30:70, respectively. The samples are then rinsed at ambient temperature with tap water to remove the pyridine and are then air dried. Thereafter the sample test and a control sample are dyed by immersing them in similar aqueous dyebaths (liquor to goods ratio being 40:1) and heating the dyebaths over a period of 30 minutes to the boil and then maintaining the dyebaths at the boil for 1 hour. The aqueous dyebaths contain 0.23% of C. I. Direct Blue 71 and 3.0% of ammonium acetate. The test sample as compared to the control sample indicates that the uniformity of dyeing was improved by the pyridine/ water solution.

EXAMPLE 7 Samples of acid dye resist nylon yarns are treated as described in Example 2 except the solutions contain the below indicated substituted pyridine compound and water at a weight ratio of 30:70, respectively. The substituted pyridine compounds are 1) cetyl pyridinium bromide (2) quinoline (3) pyridine hydrochloride The test samples as compared to control samples indicated that the above pyridine compounds are useful to increase the dye receptivity of the test samples.

EXAMPLE 8 Samples of regular nylon are immersed for 5 minutes in a boiling solution containing pyridine and water at a weight ratio of 30:70, respectively, and are then rinsed with tap water at ambient temperature to remove the pyridine. Thereafter the samples are dyed by immersing them for 60 minutes at 100 C. in aqueous dyebaths (liquor to goods ratio being 40: 1) containing.

Dyebath #1:

4% C. I. Basic Red 17 3% ammonium acetate 1% acetic acid Dyebath #2:

4% C. I. Disperse Blue 3 Dyebath #3:

4% C. I. Acid Blue 1% acetic acid The test samples compared to control samples indicate the pyridine/water solution improved the dye receptivity of the samples.

The above examples are presented to merely illustrate working embodiments of the invention and the conditions, i.e. temperature, times and concentrations are not to be considered as a limitation of the invention but as examples of working embodiments thereof.

What is claimed is:

1. A process of increasing dye receptivity of an undyed textile article produced from a fiber-forming synthetic linear polycarbonamide having recurring amide groups as integral parts of the main polymer chain comprising contacting at a temperautre of at least about 25 C. and for at least about one minute the article with a solution consisting essentially of a compound selected from the group consisting of pyridine and a substituted pyridine compound and water at a weight ratio of from about 95.5 to about 5.95, respectively, and then rinsing the article with Water to remove the pyridine or the substituted pyridine compound therefrom.

2. The process of claim 1 wherein the article is contacted for at least about 5 minutes.

3. The process of claim 1 wherein the article is con tacted at a temperature Within the range of from about 40 C. to about the boiling point temperature of the solution.

4. The process of claim 1 wherein the solution consists essentially of a compound selected from the group consisting of pyridine, lutidine, collidine, picolinic acid, nicotinic acid, isonicotinic acid, quilonic acid, quinoline, cetyl pyridinium bromide and pyridine hydroxylchloride.

5. The process of claim 1 wherein the solution contains pyridine and water.

6. A process of increasing the dye receptivity of an undyed textile article produced from a fiber-forming synthetic linear polycarbonamide having recurring amide groups as integral parts of the main polymer chain comprising contacting at a temperature Within the range of from about 40 C., to about the boiling point temperature and for a period of time of about 5 minutes the article with a solution consisting essentially of pyridine and Water at a weight ratio of from about 90:10 to about 10:90, respectively, and then rinsing the article with water to remove the pyridine from the article.

7. The process of claim 6 wherein the article is con tacted at the boiling temperature of the solution.

8. The process of claim 6 wherein the solution consists essentially of pyridine and water at a weight ratio of about :70, respectively.

References Cited UNITED STATES PATENTS 11/1968 Mautner et a1. 8-550 10/1966 Mautner, et al. 8--42 US. Cl. X.R. 8-85, 172, 178 

